Vacuum power clutch



Nov. 28, 1939.

J. H. K. M CQLLUM ET AL VACUUM POWER CLUTCH Original Filed Jan. 17, 1951 INVENTOR5 l/enryfDe/V McCuZlum James H- h. MCCoZlum ATTORNEY.

Patented Nov. 28, 1939 unit so 7 STATES z,1a1,4a1

, vacuum rowan cwrcn James a. muccoum and Henry 1.130 N. 110- Ooilum, Long Branch, N. J.

Original application January l'I, 1931, Serial-No. 509,810. Divided and this application January 21, 1882, Serial No. 581, 80 I 1: Claims. (01. 192-411) Our invention relates to improvements in vacuum power clutches and the objects of our improvements are, first, to provide an automatic power clutch mechanism which will start the motor vehicle from a standstill in a very smooth manner and without any jerking, second, to provide a power clutch mechanism which will allow of gradual and smooth acceleration in all speeds and gears, third, to provideb. power clutch mechanism which will permit of free-wheeling, or coasting, in any gear, including reverse, and which will at the same time, allow using the engine as a brake when going down very steep grades, or at any other time and in any gear, fourth, to provide a power clutch mechanism which will allow the use of the left foot for operating the service brake while the accelerator is being operated by the right foot, thus preventing back-rolling on ufi-grades in the most effective manner, fifth, to provide an automatic vacuum power clutch mechanism which will permit of driving, free-wheeling, or coasting, and braking with the engine, in any gear forward or reverse without touching the clutch pedal and by the sole manipulation of the accelerator only, and to produce a twostage clutch engaging movement which will permit a rapid initial closing movement of the clutch-actuating member until an initial engagement has been produced, and thereafter a slower movement of said member while completing said engagement. Another object is the development of a simple device by which the operation of a servomotor which opens and closes the clutch in the car transmission is made subject to step-by-step control by the operator through the accelerator.

The present application constitutes a division of our application 8.. N. 509,310 filed January 17, 1931, being confined to the particular embodiment of the-broad invention there disclosed and claimed whichinvolves the use of an air cushion for the production of such step-by-step control, as contradistinguished from the throttling of the inflow of air to the vacuum chamber of the pneumatic servomotor, which latter method of 45 step-by-step control is illustrated in Figs. 3 and' 4 of our said copending application S; N. 509,310. The best forms of apparatus at present known to us embodying sundry modifications of our 0 invention are illustrated in the accompanying sheet of drawings inwhich: Fig. 1' is a diagrammatic vertical section of a power-operated clutch controlling apparatus with its attachment to certain parts of a motor car, which latter parts are shown broken away, both ends of the power cylinder being closed; and

Fig. 2 is a fragmentary view showing a modification of the type of apparatus in which a leakage port 58 shown in Fig. 1 is omitted. 00 In the drewins ke ef re ce ch racters indicate likeparts; Inall forms of the invention here illustrated the clutch is actuated by a servomotor comprising a pneumatic cylinder containing a piston which is drawn inwardly todisengage the clutch when the interior of that end of the cylin-, 8 der is connected to the intake manifold of the motor, and the clutch engagement is produced by the action of the usual clutch springs when the connection from one end of to the intake manifold has been cut off. andzair is allowed 10 to enter that end of the cylinder the cylinder to equalize more or less nearly the pressures on the two sides of the piston. Such clutch closing movement is wholly or mainly controlled through regulation of the outflow of any air 15 I trapped in the other, substantially closed, end of the cylinder by means of a suitable valveoperatively connected to the accelerator.

Referring to Fig. 1, the usual clutch pedal of a motor car is shown at 2, a portion of the chassis 20 of which car is shown at 48. This pedal is mounted on the clutch lever I, which is keyed to the clutch operating shaft la and normally held in a clutch engaging position by the tension of the spring 20.

I5 is a section of the intake manifold of the motor to which the combustible mixture is admitted through the carbureter 21 having a throttle valve 28 of the usual butterfly type operated by the throttle lever 30 and limited in its movements by the adjustable stop mechanism 28 co- 0 operating with the fixed stop rib 29a. This throttle valve is normally held in nearly closed or idling position by the spring 8| anchored at 80. It can be opened by motion of the ac-' celerator pedal I mounted on rod 39 projecting through foot-board 8 and having a pivotal connection at 40 to the accelerator rod 38 which has a lost motion connection to the throttle rod 38 which is pivoted to the throttle lever 30. v The sleeve 81 is adjustably mounted on the end of 40 the rod 36 by means of the screw thread connection there shown and can be locked in any position of adjustment by the lock-nut l8. Throttle rod 38 slides in this sleeve and when the accelerator pedal I is fully retracted by the Q action of spring 54, there is a gap left between the end of rod 88 and the end of the accelerator rod 88. Ports 58 admit air to this space so as to permit free movement of-- the parts. When the accelerator pedal I is forced by the operator's foot toward the left the first action will be to take up the lost motion and thereafter subsequent movement of the pedal will causeopenin movement of the throttle valve.

The power mechanism or servomotor for operating the clutch shown in this figure comprises the vacuum cylinder 9 which is pivotally mounted on the chassis 46 by means of the pedestal 41 fastened to the chassis by screw bolts 5|, BI, and the lug l8 projecting beyond the closed end of the cylinder and hinged or pivoted to the pedestal 41 at, together with the piston l9 reciprocable in said cylinder.

0n the outer end of the piston rod 3 is the screw thread 5 by means of which it is adjustably connected to the fork 4 which carries the pin 52 in its open end, forming a pivotal connection with the pedal lever 8 is a lock-nut on the piston rod. The left hand end of cylinder 9 is connected through port l2a to the port casing 20 mounted on the casing I8 ofthe double piston valve l5 and surrounding ports I 9 there- .in. Said valve is connected by pin to rod 39 so as to be reciprocable by accelerator 1. Its piston section 34 is just wide enough to lap ports l9, and its cutaway portion |8 between said piston 34 and the one 33 at its left hand end is wide enough to connect said ports l9 with another valve casing port 2| when the accelerator 1 has been put in fully retracted position by contraction of spring 54, and valve l5 thereby also moved to the right far enough to place its piston section 34 to the right of ports-l9. Piston section 33 is always to the left of port 2| which is connected by conduit 26 to manifold 25. Said conduit as shown is made in two sections connected by a short length of rubber tubing i4 fastened thereto by hose clips 55, 55, so as to permit cylinder 9 to swing slightly on pivot 58. The above described balanced valve mechanism operates to admit air at atmospheric pressure to cylinder 9 when valve I5 is in any position with its piston portion 34 to the left of the right hand edges of ports l9, to subject said cylinder interior to manifold suction whenever said valve portion 34 has moved to the right of the lefthand edges of said ports, and to trap the contained air in cylinder 9 whenever said portion 34 is in position for bridging ports l9.

The middle portion of the piston rod 3 in this case is made hollow havingthe bore 96 connected to the right hand portion of the interior of cylinder 9 by port 95 near the piston and to the atmosphere through ports 91 near the outer end of the piston rod; ports 91 are controlled by a valve sleeve 98 sliding on the piston rod and connected by pivoted link 9|, a walking beam 90, pivoted link 89 and pivot lug 81 to the valve rod 39. Walking beam 90 vibrates on a fixed pivot in fork 93, supported by housing 92, which is fixed on cyl nder head 4|. 94 is an inwardly opening spring-closed air valve mounted in said head 4|. The slow final movement of the piston is here caused by the trapping 'of air in the ri ht-hand end of the cylinder when the ports 91 in the piston rod enter sleeve 98. Thereafter the trap ed air slowly escapes through the leakage port 56 in the walls of cylinder 9 near the r ht hand end thereof.

When the pedal 1 is in its farthest position to the right, the sleeve 31 has slid to the right on the rod 38, after the throttle closed, thus leaving a ap between the end of the rod 38 \and the end of rod 36; but with the parts in the 65 position shown the end of the rod 38 is in contact with the end of rod 36 so that the throttle is operated by any further movement of pedal 1 to the left. Holes 58 in sleeve 31 serve to prevent air locks, which might prevent quick atmosphere continuously, and simultaneously disconnect the rest of the mechanism from said cy1inder, if it is desired to run the car in the. ordinary manner without using our invention, or the piping can be so arranged as to permit the use of one double three-way combination'valve for these purposes.

The spring 54, yielding toa light tension, allows of an additional resistance being felt by the operator's foot resting on pedal 1 whenever the end of rod 38 comes against the end of rod 86, the added resistance of spring 8| then coming into action as the throttle of the carbureter 28 then begins to open slowly from the idling position. When this resistance is felt by the foot the operator will know that the right position of the parts for using the engine as a brake, or for running the car slowly with the carbureter in idling position, has been obtained, because this resistance can be felt by the foot without even moving the carbureter throttle valve from its idling position. In fact the best position for the parts for using the engine as a brake is just at the point where this resistance is felt by the foot, the carbureter throttle being still in an idling position.

If desired, the ports 56 -can be dispensed with as indicated in Fig. 2, since there probably will be enough leakage of air passing piston [0, or around piston valve i5, to allow complete clutch closure to be ultimately effected, even if valve sleeve 98 is left in a position lapping ports 9'! after a gear shifting operation has been completed and while the car is rimning with its throttle only slightly opened.

Also, another method of using the engine as a brake can be employed in any case; that is, the pedal 1 can be moved far enough to the left to give a rapid and full engagement of the clutch as above described, and then such pedal can be allowed to move back to the right until there occurs a reduced pressure against the operators foot, caused by the cessation of the effective tension of the spring 3|, which then can no longer be felt, thus bringing the parts into the position shown.

While the car is free wheeling at a high speed, if the parts afe put into positions shown the engine, which is then idling, can be picked up, i. a. connected to the driving shaft and rear axle and brought up to a speed corresponding to that at which the car is moving, without any jar or jerk beling felt. Thereafter pedal 1 can be moved farther to the left to give the clutch its full engagement and to thereafter increase the power of the motor to any desired extent.

To satisfy the various conditions of starting, free wheeling or coasting, driving, or braking with the engine, and changing gears at various car and engine speeds, a rapid disengagement of the clutch up to a variable degree of initial engagement for the existing engine speed, and a variable rate of the completion of engagement of said clutch from the point of said initial engagement, are all necessary, and to suit these conditions we have devised the form of. our invention which is shown in Fig. 1, in which a timing of the initial action of the valve which produces the change from the first to the second stage of clutch engaging movement may be eifected by the operator's manipulation of accelerator pedal 1.

The mode of operation of that embodiment of our invention, the leakage port 55 being retained as there shown, is as follows: As pedal 1 is deanswer pressed to a point where the, lost motion in the throttle connection has been taken up, .as shown,

the part of the cylinder interior to the left of the piston I9 is disconnected from the intake manifold 25 and connected to the atmosphere through the right hand openend of valve casing II; The valve sleeve 96 has been moved into the position shown and the ports 91 in the hollow piston rod have been closed by the motion to the right of said hollow piston rod 3. Suflicient pressure has been formed in the cylinder, to the right of the piston III, to check further movement of the piston as the air so trapped can no longer flow out through the ports 96, bore or passage-' way 96 and ports 91. When the piston has reached this point .the clutch is partially engaged, and thereafter the leakage'port 56 acts,\permitting further slow movement of the pistontill it closes port 56, if the accelerator 1 is held stationary. By further depressing pedal I, an increased degree of engagement .ofthe clutch is initially obtained as the piston Iii-must move further to the right before closing the ports 91. When pedal 1 is released and retracted by spring 54, the piston valve i5 moves to the right, thus disconnectmovement of piston rod 3 through sleeve 99 to the left.

After the clutch closing movement of piston 9 has caused it to lap leakage port 66, all furtherprogress in clutch closure is under practically complete'step-by-step control of the accelerator, there being then no escape for the air trapped in that end of cylinder 9 other than through ports since no automatically produced second and slower stage of such piston movement can then occur while the accelerator is held stationary, such as may occur when port 56 is retained, as in Fig. 1.

The rubber hose sections it, I 4, will not collapse even under the maximum partial vacuum created in them, if made with thick walls, such as are now common in the hose used on tire pumps.

In starting the car, or in ree'ngaging the clutch after a gear shifting operation the accelerator can be pressed down slowly until an initial clutch engagement is efiected and then held stationaryv a moment till the follow-up action of the piston rod causes ports 91 to be closed by passing into the interior of sleeve 99, which will practically stop the clutch closure at that point if leakage port 56 has been omitted, as in Fig. 2, or if piston lil has theretofore moved far enough to the right to have closed said port, .thus avoiding jerking the car, practically simulating the action of a skillful operator when manipulating the clutch by means of pedal 2. After the car has begun to move when starting, or has increased its speed after shifting gears, the accelerator can be pressed I 3 down. further, thus increasing both the amount of pressure between the clutch faces and the amount of power being delivered by the engine for transmission by the clutch, and inthis way the full clutch engagement and generation of power for transmission thereby can beaccomplished contemporaneously in stages, step-bystep. e

' If the leakage port '56 retained, as shown in Fig. Land has not theretoi'ore been closed by piston in, by the time the clutch closing motionv of the accelerator is stopped'the very slow'continuing outflow of air through said port will permit a very slow continued closing movement of the clutch so long as the accelerator is held stationary. Consequently theslow completion of clutch engagement (if accomplished before piston it closes port 56) is theneflected automatically, while with the modification shown in Fig; 2

it isunder absolute control of the operator from initiation to termination,-all as hereinbefore explained. Having described our invention, we claim:

1. In anapparatus for actuating by fluid pressure a movable member of a mechanism adapted to operate a power transmitting clutch such as is employed in motor cars, the combination, with said above described apparatus, of automatic means adapted to produce a relatively rapid flow of the fluid to effect a correspondingly rapid clutch engaging movement of said clutchoperat- 'ing member followed by a relatively slower flow or said fluid during the final stages of said engaging movement, comprising a cylinder containing a piston and having a closed end through which the piston rod projects and is 'operatively connected to said movable member; said piston rod being hollow and having one air outlet port near thepiston between the latter and that cylinder head through which saidrod projects and inder containing a piston and having a closed end through which the piston rod projects and is operatively connected to said movablemember; said piston rod being hollow and having one air outlet port near the piston and another near its outer end, and means for closing said outer port comprising a sleeve on the extension of said piston rod and through which said rod normally moves as said piston travels in said cylinder, said cylinder having a pemanently open air leakage port located adjacent said closed end thereof.

4. A pneumatic apparatus for actuating a mov- .able member of a mechanism adapted to operate the power transmission clutch of a motor car, comprising, in combination, a cylinder closed at both ends but connected to the intake manifold of the car motor at one end and having a piston with a hollow piston rod projecting through the other end, said hollow piston rod having one port near said pistonand another near its outer end, a valve controlling said intake manifold connection and capable of move ment beyond its initial closing position, a sleeve on the exterior of said piston rod and through which said outer ported portion of said, rod is sleeve and adapted to cause said sleeve to move farther away from said cylinder as said valve in the intake manifold connection is moved beyond its initial closing position; whereby, on any outstroke of said piston following the closure of said manifoldconnection said outer piston rod port is closed at a predetermined point and air thereby trapped in that end of said cylinder, but, on a further movement of said valve in the direction which produced said initial closure, said piston rod port is redpened and further escape of air therethrough from the cylinder is permitted until it is again closed by further resultant movement of the piston and piston rod.

5. In a pneumatically actuated apparatus for operating the clutch lever of a motor car comprising spring means for moving said lever into a position producing clutch engagement, a cylinder closed at one end except for a port through which air may be admitted to and withdrawn from it, and means for soadmitting air therethrough, together with a piston in said cylinder and a closure for the other end thereof toward which end said piston moves to produce said clutch engaging movement of said lever, the combination, with said above described apparatus, of a piston rod connecting said piston and said lever, extending through said closure and having a passage extending lengthwise thereof for permitting the escape of air from that end of such cylinder, and manually adjustable means for preventing further escape of air when said piston movement has reached a point producing a selected degree of clutch closure.

6. A combination such as defined in claim 5 in which said passage extends through the interior of said piston rod, but has an opening at either end.

7. In an apparatus of the class described, a servo-motor operable by fluid pressure and comprising a cylinder closed at one end, a piston reciprocable in said cylinder, and a piston rod rigidly fastened to said piston and projecting through said closed cylinder end, combined with a movable clutch-controlling member to which the projecting end of said piston rod is connected; said piston rod having a passageway extending longitudinally of its interior, one end of which passageway is in constant communication with that portion of said cylinder interior between its said closed end and said piston, while the other end of said passageway has an opening to the atmosphere during the first portion only of the clutch-engaging movement of said piston.

8. In an apparatus of the class described, a

servo-motor operable by fluid pressure and comprising a cylinder closed at one end, a single, imperforate piston reciprocable in-said cylinder, and a piston rod rigidly fastened to said piston and projecting through said closed cylinder end, combined with a, movable clutch-controlling member to which the projecting end of said piston rod is connected; said piston rod having a passageway extending longitudinally of its'interior, one end of which passageway is in constant communication with that portion of said cylinder interior between its said closed end and said piston, while the other end of said passageway has an opening to the atmosphere during the first portion only of the clutch-engaging movement of said piston; together with means for automatically closing said opening to the atmosphere during a subsequent portion of said clutch-closing movement of said piston.

9. In a servomotor for opening and closing the clutch of a motor car comprising a'cylinder with closure heads at both ends, a piston reciprocable therein, and a conduit opening into the cylinder interior through one of said heads adapted for exhausting air therefrom, the combination of a hollow cylindrical piston rod of uniform external diameter extending from said piston through the other of said heads having a substantially airtight, sliding bearing therein and a port connecting its bore with the interior of that end of said cylinder, with means for operatively connecting the projecting portion of said piston rod with a clutch actuating member, and manually adjustablemeans for controlling the flow of air through said port.

I 10. A combination such as defined in claim 9 in which said manually adjustable means comprises valve mechanism and a device for adjusting the position of a movable element thereof adapted to be operatively connected to the accelerator of any car on which such servomotor may be installed.

11. A combination such as defined in claim 9 in which said piston rod bore is closed at its outer end except for a port through its side walls located exteriorly of the adjacent cylinder head, and in which said manually adjustable means comprises a valve sleeve fitting closely on said piston rod and adapted to open or close said port by virtue of proper relative reciprocation between them.

12. In an apparatus of the class described, a servo-motor operable by fluid pressure and comprising a cylinder closed at one end, a piston reciprocable in said cylinder, and a piston rod rigidly fastened to said piston and projecting through said closed end, combined with a movable clutch-controlling member to which the projecting end of said piston rod is connected; said piston rod having a passageway extending longitudinally of its interior, provided with an opening through its wall near one of its ends so located as to remain always within said closed cylinder end during substantially the entire of the normal reciprocating motion of said piston, while the other end of said passageway has an opening to the atmosphere.

13. In an apparatus of the class described, a servo-motor operable by fluid pressure and comprising a cylinder closed at one end, a piston reciprocable in said cylinder, and a piston rod rigidly fastened to said piston and projecting through said closed end, combined with a movable clutchcontrolling member to which the projecting end of said piston rod is connected; said piston rod having a passageway extending longitudinally of its interior, provided with an opening through its wall near one of its ends so located as to remain always within said closed cylinder end during a major portion at least of the normal reciprocating motion of said piston, while the other end of said passageway has an opening to the atmosphere, together with manually adjustable means for controlling the flow of air through said passageway.

HENRY J. DE N. McCOLLUM. JAMES H. K. McCOLLUM. 

